I've already made an account, but I want to add a new site to that account to place ads on.. Does google need to approve the site before I slap Ads on it?
you just have to put the adsense code on the new site. You can use the same code on as many sites as you want (as long as they follow the adsense terms)
Once you got an Adsense account, you can put your ads code in unlimited amount of your websites. You do not have to report or ask for approval from google everytime you put an ads on new site. just make sure one thing that your site is not against google TOS.